The candidates agreed that the U.S. economy needs to grow more rapidly. What they argued over is whose economic plan will make it grow faster.

The push for economic growth has become sacrosanct in modern political discourse. Growth is the elixir that heals all social and economic divisions and makes possible the solidarity that comes from the feeling that the path to wealth is open to everyone.

For the vast majority of people on the planet that path was never really open. And, since the so-called Great Recession, it has been closed off completely for all but those at the top of the income scale.

There are many explanations. But most of them are financial and political. The world's economists and political leaders are ready with both diagnoses and prescriptions for lackluster growth throughout the world. However, the laws of physics, chemistry and biology never enter their heads.

Growth is supposedly something that comes from the "minds of men." (Pardon me, women, for it is men who mostly say this.) While there is truth to the idea that the cleverness of humans has accounted in part for the astonishing growth of the world economy in the last three centuries, it is more true that humans have leveraged increasingly available fossil fuel energy to achieve that growth.

Without fossil fuels, we as a species would not appear so clever. And we must keep in mind that we did not invent coal, natural gas or oil. In fact, our extraction and use of them more closely resembles the pattern of a hunter-gatherer society than of a modern agricultural one.

We know that on our current growth trajectory we will cause irreparable damage to the climate and the biosphere upon which we depend. The hope is that somehow we can prevent this damage with technology that won't require giving up on economic growth. While anything is possible, the odds are stacked gravely against such an outcome.

We are pursuing incommensurable goals by saying that we must lift all those still in poverty out of it--with little or no redistribution of wealth--while preserving the biosphere and the climate. We are not taking the second part of this proposition seriously or we would understand that the first part--under current definitions of wealth (meaning increased use of energy and resources)--will necessarily destroy the world in which we hope to enjoy this wealth.

Some may say that this is not a sure thing, that we can't really know this. In a very narrow sense, they are right. If only the risks were trivial, we could wait to see. But the risks are monumental and, in fact, existential. Under such circumstances, we should not ask for absolute certainty, but rather inquire about the weight of the evidence from our observations and the models of Earth systems as we understand them.

However imperfect our understanding, the evidence and models are all flashing major warning signs. This is not a one-alarm fire; this is a million-alarm fire. We have vast areas of agreement from disparate disciplines that something is seriously wrong with planet Earth from the coral reefs all the way up to the ozone layer in the stratosphere.

We are too many people consuming too much per person and creating waste in the form of greenhouse gases that are overwhelming the Earth's natural thermostat. The solution to our problems cannot be to do more of the same.

And yet, that is precisely what both major U.S. presidential candidates champion. It is, of course, political suicide to propose a downsizing of American life to something commensurate with the survival of advanced human societies. Such a downsizing would have to coincide with much greater redistribution of existing wealth in order to insure social peace--which is why politicians of all kinds avoid the issue.

Yet, the issue remains, and from here on out it can be framed as follows: Will ignoring the imperative to redefine completely what makes our lives good--that is, beyond more resources--lead to suicide that is of an entirely different order?

In the past we've had the luxury of pretending that we could grow our economy forever. We don't have that luxury any more. Continued exponential growth will extract heavy costs. In fact, it already has.

Kurt Cobb is an author, speaker, and columnist focusing on energy and the environment. He is a regular contributor to the Energy Voices section of The Christian Science Monitor and author of the peak-oil-themed novel Prelude. In addition, he has written columns for the Paris-based science news site Scitizen, and his work has been featured on Energy Bulletin (now Resilience.org), The Oil Drum, OilPrice.com, Econ Matters, Peak Oil Review, 321energy, Common Dreams, Le Monde Diplomatique and many other sites. He maintains a blog called Resource Insights and can be contacted at kurtcobb2001@yahoo.com.